1. The Periodic Table
SC1. Obtain, evaluate, and communicate information about the use of the modern atomic theory and periodic law to explain the characteristics of atoms and elements.
f. Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms (i.e. including atomic radii, ionization energy, and electronegativity).
g. Develop and use models, including electron configuration of atoms and ions, to predict an element’s chemical properties.

2. Ancient Times
330 BC – Aristotle proposed that everything was made of a mixture of one or more roots, later called elements by Plato: earth, fire, water, and air 1649 – Brand discovered phosphorus while trying to discover the Philosopher’s Stone 1789 – de Lavoisier wrote the first textbook on chemistry in which he listed several “simple substances” which he claimed could not be broken down any further. He also classified substances into metals and nonmetals.

3. Dobereiner
1829 – Developed the Law of Triads, observing that if groups of chemically similar elements were arranged in increasing order of their atomic weights, they formed well marked groups of three called triads

4. De Chancourtois
1862 – The first person to recognize the repeating patterns of the elements when arranged by their atomic weights

5. Newlands
1864 – Noted that many pairs of similar elements existed, which differed by some multiple of eight in mass number – termed the Law of Octaves. He was the first to assign atomic numbers to elements and contributed the word “periodic” in chemistry.

6. Mendeleev
1869 – Published the first table of the elements organized by increasing atomic mass.

7. Elements known in Mendeleev’s time

8. Mendeleev stated that...
If the elements are arranged according to their atomic mass, they exhibit apparent periodicity of properties
Elements which are chemically similar have atomic weights that are similar or increase regularly
The arrangement of the elements corresponds to their valencies and to their distinctive chemical properties

9. Mendeleev stated that...
If the atomic weight of an element may sometimes be amended by a knowledge of those contiguous to it (he corrected the atomic masses of Be, In, and U)
One should expect the discovery of many yet unknown elements
Certain characteristic properties of elements can be foretold from their atomic masses

10. After the discovery of these unknown elements between 1874 and 1885, and the fact that Mendeleev’s predictions for Sc, Ga, and Ge were amazingly close to the actual values, his table was generally accepted.

11. However, in spite of Mendeleev’s great achievement, problems arose when new elements were discovered and more accurate atomic weights determined. By looking at our modern periodic table, can you identify what problems might have caused chemists a headache?
Ar and K
Co and Ni
Te and I
Th and Pa

12. Moseley
1914 – Through his work with X-rays, he determined the actual nuclear charge (atomic number) of the elements*. He rearranged the elements in order of increasing atomic number.
*“There is in the atom a fundamental quantity which increases by regular steps as we pass from each element to the next. This quantity can only be the charge on the central positive nucleus.”

13. Seaborg
1944 – After co-discovering 10 new elements, he moved 14 elements out of the main body of the periodic table to their current location below the lanthanide series.
These became known as the actinide series.

14. Seaborg
He is the only person to have an element named after him while still alive.
"This is the greatest honor ever bestowed upon me - even better, I think, than winning the Nobel Prize."

16. Periodic Table Geography

17. The horizontal rows of the periodic table are called PERIODS

18. The elements in any group of the periodic table have similar physical and chemical properties!
The vertical columns of the periodic table are called GROUPS, or FAMILIES

19. Periodic Law
When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties.

20. Alkali Metals Soft, silvery, highly reactive metals
Second most reactive group
Only found in combined state in nature
Form alkaline/basic compounds with water
Alkali Metals

21. Alkaline Earth Metals Harder, silvery, less reactive metals
Readily form oxides, which produce alkaline compounds in water
Alkaline Earth Metals

22. Transition Metals Most “metal-like” High hardness and density
Very conductive
Transition Metals

23. Inner Transition Metals
Generally, lanthanides are naturally occurring.
All actinides are radioactive and most are synthetic.
Inner Transition Metals

24. Halogens Nonmetals; all 3 states represented Most reactive group
Only found in combined state in nature
Toxic to living organisms
Halogens

25. Noble (Inert) Gases Virtually unreactive gases
Most stable elements on the PT
Noble (Inert) Gases

27. Properties of Metals Metals... are solid (except Hg, a liquid)
are good conductors of heat and electricity
are lustrous (shiny)
are ductile (can be stretched into thin wires)
are malleable (can be pounded into thin sheets)
have higher density
have higher MP/BP
are electropositive

28. Properties of Nonmetals
are poor conductors of heat and electricity
are brittle, if solid
are not lustrous, ductile, or malleable, if solid
are solid, liquid or gas (most)
are electropositive
have lower density
have lower MP/BP
Sulfur

29. Properties of Metalloids
have physical properties of metals and chemical properties of nonmetals
are solids that can be shiny or dull
conduct heat and electricity better than non- metals but not as well as metals (semi-conductors)
can be ductile and malleable or brittle
Silicon

30. The periodic table is the most important tool in the chemist’s toolbox!